Sodium iodide effects on the helical stability of a mainly alanine peptide Downey, Theresa; Asciutto, Eliana; Madura, Jeffry Bioinformatics-Bioengineering-Summer-Institute Department of Computational Biology University of Pittsburgh Department of Chemistry and Biochemistry Center for Computational Sciences Duquesne University Peptide-based drugs have the potential to treat many diseases. Some α-helical peptides have the ability to enter cells by crossing the lipid bilayer. However, the environment could affect the peptide’s α-helical stability and hinder its entrance into the cell. To overcome this difficulty both experimental and computational teams have developed various techniques to stabilize the α-helix configuration of peptides. One method is to select ions to stabilize the α-helix secondary structure in an aqueous environment. This work studied the stabilization effects of the iodide anion on a mainly alanine peptide as a portion of the entire Hofmeister series investigation. Additionally, Replica Exchange Molecular Dynamics was employed to increase the sampling of configurations of the system throughout simulation. According to previous studies, the iodide ion is expected to stabilize the peptide less than perchlorate in an aqueous environment according to the Hofmeister series.